generateDataKeyPairWithoutPlaintext method

Future<GenerateDataKeyPairWithoutPlaintextResponse> generateDataKeyPairWithoutPlaintext({
  1. required String keyId,
  2. required DataKeyPairSpec keyPairSpec,
  3. Map<String, String>? encryptionContext,
  4. List<String>? grantTokens,
})

Generates a unique asymmetric data key pair. The GenerateDataKeyPairWithoutPlaintext operation returns a plaintext public key and a copy of the private key that is encrypted under the symmetric CMK you specify. Unlike GenerateDataKeyPair, this operation does not return a plaintext private key.

To generate a data key pair, you must specify a symmetric customer master key (CMK) to encrypt the private key in the data key pair. You cannot use an asymmetric CMK or a CMK in a custom key store. To get the type and origin of your CMK, use the KeySpec field in the DescribeKey response.

You can use the public key that GenerateDataKeyPairWithoutPlaintext returns to encrypt data or verify a signature outside of AWS KMS. Then, store the encrypted private key with the data. When you are ready to decrypt data or sign a message, you can use the Decrypt operation to decrypt the encrypted private key.

GenerateDataKeyPairWithoutPlaintext returns a unique data key pair for each request. The bytes in the key are not related to the caller or CMK that is used to encrypt the private key.

You can use the optional encryption context to add additional security to the encryption operation. If you specify an EncryptionContext, you must specify the same encryption context (a case-sensitive exact match) when decrypting the encrypted data key. Otherwise, the request to decrypt fails with an InvalidCiphertextException. For more information, see Encryption Context in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. To perform this operation with a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:GenerateDataKeyPairWithoutPlaintext (key policy)

Related operations:

May throw NotFoundException. May throw DisabledException. May throw KeyUnavailableException. May throw DependencyTimeoutException. May throw InvalidKeyUsageException. May throw InvalidGrantTokenException. May throw KMSInternalException. May throw KMSInvalidStateException. May throw UnsupportedOperationException.

Parameter keyId : Specifies the CMK that encrypts the private key in the data key pair. You must specify a symmetric CMK. You cannot use an asymmetric CMK or a CMK in a custom key store. To get the type and origin of your CMK, use the DescribeKey operation.

To specify a CMK, use its key ID, Amazon Resource Name (ARN), alias name, or alias ARN. When using an alias name, prefix it with "alias/". To specify a CMK in a different AWS account, you must use the key ARN or alias ARN.

For example:

  • Key ID: 1234abcd-12ab-34cd-56ef-1234567890ab
  • Key ARN: arn:aws:kms:us-east-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab
  • Alias name: alias/ExampleAlias
  • Alias ARN: arn:aws:kms:us-east-2:111122223333:alias/ExampleAlias
To get the key ID and key ARN for a CMK, use ListKeys or DescribeKey. To get the alias name and alias ARN, use ListAliases.

Parameter keyPairSpec : Determines the type of data key pair that is generated.

The AWS KMS rule that restricts the use of asymmetric RSA CMKs to encrypt and decrypt or to sign and verify (but not both), and the rule that permits you to use ECC CMKs only to sign and verify, are not effective outside of AWS KMS.

Parameter encryptionContext : Specifies the encryption context that will be used when encrypting the private key in the data key pair.

An encryption context is a collection of non-secret key-value pairs that represents additional authenticated data. When you use an encryption context to encrypt data, you must specify the same (an exact case-sensitive match) encryption context to decrypt the data. An encryption context is optional when encrypting with a symmetric CMK, but it is highly recommended.

For more information, see Encryption Context in the AWS Key Management Service Developer Guide.

Parameter grantTokens : A list of grant tokens.

For more information, see Grant Tokens in the AWS Key Management Service Developer Guide.

Implementation

Future<GenerateDataKeyPairWithoutPlaintextResponse>
    generateDataKeyPairWithoutPlaintext({
  required String keyId,
  required DataKeyPairSpec keyPairSpec,
  Map<String, String>? encryptionContext,
  List<String>? grantTokens,
}) async {
  ArgumentError.checkNotNull(keyId, 'keyId');
  _s.validateStringLength(
    'keyId',
    keyId,
    1,
    2048,
    isRequired: true,
  );
  ArgumentError.checkNotNull(keyPairSpec, 'keyPairSpec');
  final headers = <String, String>{
    'Content-Type': 'application/x-amz-json-1.1',
    'X-Amz-Target': 'TrentService.GenerateDataKeyPairWithoutPlaintext'
  };
  final jsonResponse = await _protocol.send(
    method: 'POST',
    requestUri: '/',
    exceptionFnMap: _exceptionFns,
    // TODO queryParams
    headers: headers,
    payload: {
      'KeyId': keyId,
      'KeyPairSpec': keyPairSpec.toValue(),
      if (encryptionContext != null) 'EncryptionContext': encryptionContext,
      if (grantTokens != null) 'GrantTokens': grantTokens,
    },
  );

  return GenerateDataKeyPairWithoutPlaintextResponse.fromJson(
      jsonResponse.body);
}